Process of producing substantially pure magnesium



June 4, 1935. F. HANSGIRG 2,003,487

PROCESS OF PRODUCINGSUBSTANTIALLY PURE MAGN'ESIUM Filed Feb. 5, 1933 lsheets-sheet 1 Invenfor q l June 4, 1935.

F. HANsGlRG PROCESS OFA PRODUCING SUBSTANTALLY PURE MAGNESIUM .Filed Feb. s. i935 Fig.2

fner/gas 4Sheets-Sheet 2 NIsae* In ven for 6km, m

June 4, 1935.

File'd Feb. 5, 1933 4 Sheets-Sheet 4 mp hm m m, WP m .m u i IN E 'R- 6014,

WITNSSES Patented June 4, 1935 y -raocEss or raonucnrc sUsTANTTALLYf -ruau MAGNnsroM Frm neming, mummia-sum1, assigner fo Americanv ,Magnesium Metals Corporation,

Pittsburgh, Pa., a corporation of Delaware l Application Februa 3, 1933, Serial No. 655,06'1v In Austria February 11, 1932 1s claims. (ci. 75411) This invention relates to a process of and apparatus for producing substantially pure magnesium.

Like all solid 'substances having a considerable 5 vapor tension even below their melting point, metallic-magnesiumdisplays the tendency to pass directly from the condition of vapor into the solid state, without the occurrence of a liquid phase.

It has therefore been repeatedly recommendedv l0 to purify magnesium by sublimation, or to produce it in crystalline form, from magnesiumcontaining originating materials, a process which,

however, isv attended inter alia, withr the drawback, in operating on a technical scale, that it the other hand, the distillation of magnesium has hitherto encountered serious diiliculties.

One object of the present invention is to separate substantially pure magnesium from nonvolatile concomitant substances.

Another object of my invention is to enable magnesium to be distilled so as to condense the distillate as a liquid deposit.

A further object of the invention is to provide a process of and apparatus for the distillation of material containing metallic magnesium which can be carried on continuously. g

My process comprises passing crude metallic magnesium or material high in magnesium, continuously through a heated zone, in order to heat it toa temperature above the melting point, and preferably in the neighbourhood of the boiling point of magnesium,'the disengaged vapors being carried by an inert or reducing gas, through an interposed filter', into the condensing zone, the vapors being prevented from cooling below the solidification point of the magnesium, by being heated on their way to the condensing zone, and being thereafter suddenly cooled to condensation with a condenser from which the molten magsnesium runs oi into a collector, for example, through a barometric outlet, a filter being interposed between the said distillation chamber and the said condenser. The still,.fllter, condenser,

can only be performed in a periodic manner. On-

point; The filtration serves to remove con' outlet and receiver are preferably housed in a common heating chamber, such asan electric radiation furnace.

In order torender the filtration process continuous, it is advisable to employ a filter of loose, granular material, piled up loosely, between' an intake and closable outlet, in the passage connecting the still chamber with the condenser.

In a preferred embodiment of apparatus for carrying out the invention, the condenser consists 10 A A I of a hollow body', closed below and internally cooled, and preferably witha curved bottom, said body being disposed in a heated jacket, in such a manner that the incoming vapors bathe the lowest portion of the cooling surface. 'I'his cooll5 ing tube is preferably provided with a device for maintaining a liquid or gaseous cooling medium `in circulation, the arrangement being such that the, heat is transmitted through the outer tube to the cooling medium principally by radiation'. 20 To enable the cooling action to be accurately regulated, it is advisable to arrange said circulating device so as to be vertically adjustable.

In order more clearly to understand the nature of the invention, reference is made to the accom- 25 panying drawings., which illustrate diagram- -matically and by way of example, anembodiment of apparatus suitable for carrying out the process of the invention.

In said drawings'Fig. 1 shows a front elevation 30 in partial section;

Fig. 2 across section;

Fig. 3 -a'vertical section th' I embodiment; andv A Fig. 4 a detail of a further modification.

Like reference characters denote like parts in the several iiguresof the drawings.

According to the example shown in Figs. 1 and 2, the distillation chamber I is in the form of a h "a modied tube, which extends through a suitable heating 40 apparatus, such as an electric radiation furnace `2. The material to be distilled is placed in the charging-hopper -3 and passes through the lock .chamber I-the closure members 5 and 6 coacting with levers-into' a stock l vessel 1, from 45 which it is continuously fed, by means of a worm 8 or the like, into thedistillation chamber I, through which the material is conveyed by means of a worm 9 or the like. 'I'he residue falls into a collector l0, from which it is discharged through 50 a lock chamber Il, with the closure members 5 and 6B. The collector lll and chamber Il, as also the chamber 4 and stock vessel 1,are connected with the vacuum pump by means of pipes 5 adapted to be closed independently.

' Midway along its length the distillation tube I is connected by a conduit I2 with the outer shell I3 of a condenser, the discharge pipe I4 of which disposed upright in the heated shell I3, in such a manner that the incoming vapors bathe the lowest portion of the cooling surface. A tube I8 is centred in the tube I1 so as to leave a small intermediate space all round and allow the transmission of heat to take place principally by radiation and is cooled by means of a liquid or gaseous cooling medium, which is admitted through the tube I9a and passes away through the lateral branch |91. The whole of the circulation device is vertically adjustable in the tube I1, in order to enable the cooling action to be accurately regulated.

In order to remove accompanying dust, a lter is interposed in the pipe I2 connecting the chamber I with the condenser I3. The filtering medium consists preferably of loose, 'granular material, such as sintered magnesite or coal slack, disposed loosely in the connecting pipe. The arrangement shown in Fig. 2 has been adopted to enable the filtering medium to be replenished without interrupting the work. The ltering medi 20 is disposed in a hopper 2I, to the lower en of which is attached a tube 23, which can be closed by a valve 22 and dips into a collector v24, whilst a pipe 25, leading from a stock vessel 26, rests on the heap. On the valve 22 being opened, the entire column of material is set in motion, the active portion becoming changed. If desired, the valve can be left slightly open all the time, so that the changing is continuous. Since the ltering medium is more rapidly clogged up on the intake side than on the discharge side, it is advisable to arrange that the changing of the medium does not proceed with the same velocity on the two sides. For this purpose a deltoid member 21 is disposed, slightly eccentrically, in the hopper 2|, so that the outlet passage on the intake side of the vapors is Wider than the passage on the outlet side, and the medium ac,- cordingly moves more rapidly on the intake side than at .the outlet side.

In order to direct the ow of the magnesium vapors, they are conducted to the condenser by means of a current of inert or reducing gas, such 'as hydrogen. For this purpose, supply pipes 28,

- 29, 30, 3|, are employed, which, in the example shown,r are attached'at both ends of the reaction chamber I (Fig. 1) and to the stock vesselv 26 and outlet pipe 23 (Fig. 2) respectively.

The material to be distilled, such as magnesium dust, furnished by the electrothermal reduction of magnesium compounda'is heated in the heating zone to a temperature-according to the degree of vacuum-fat which the magnesium already possesses a high vapour tension, preferably to a temperature near (slightly abovfe) boiling point. The pipe I2 leading to the condenser (Fig. 1), the illter and the shell I3 of the condenser are heated to such an -extent that the Before entering the,

heated portion of the casing 32, the buckets 34 are lled with magnesium-containing material from a stock vessel 35 and this material is thereafter superposed by a filtering material discharged frorn a stock vessel 31. The outlets of each vessel are adapted to be closed by slides 36, 38 respectively. The vapors generated in the heated sectionof the tube 32 pass through the filtering medium and are carried off to the condenser I3 by means of the ushing gas admitted at 39 and 40.

In Fig. 4 there is illustrated a double receiver which may be used in connection with the present process, and which is similar to that shown in i Ullmann Enzyklopaedie der Technischen Chemie of 1929, second edition, third volume, atv page 610. It comprises two receivers 45, 45 which may be connected alternatively by means of the three way valve 46 through pipe I4 to the condenser. Each of the receivers is adapted to be connected with the vacuum pump or the atmosphere by means of pipes controlled by valves 48, 48 and 49, 49' respectively. The discharge pipes of the receivers 45 and 45 may be closed independently by valves 53 and 53 respectively. Before the distillate is allowed to flow through the pipe I4 and the valve 46 to the receiver 45, the valve 48 will be opened to provide a vacuum and the valves 49 and 53 willy be closed. Simultaneously the distillate may be discharged from the receiver 45'; for this purpose, after closing the valve 48" and opening the valve 49' the valve 53' is opened. When the receiver 45 is to receive the distillate and the receiver 45 is to be discharged the operation of the valves is reversed.

Instead of conveying the material to be distilled through the distillation zone by means of a Worm or bucket elevator, the process can also be carried out with the aid of other suitable known devices permitting the flow o1' the material under the influence of gravity (such as for instance stationary furnaces comprising a series of hearths in step relation), or by rotation of a heated tube round its long axis (such as revolving furnaces), or by stationary furnaces provided with paddle-shaped conveying devices. It is only essential vthat the magnesiferrous material pass through a heated zone so as to be brought to a temperature which causes transformation of the magnesium into the state of vapor, which temperature, of course, depends on the pressure conditions existing in the heated system, and that, after passing through a lter, the resulting magnesium vapor is subjected to such condensation conditions vthat the metal will be precipitated in liquid form. l

In all cases, heat-resisting special steels, free from nickel and copper, must be employed for constructing the apparatus of the present invention in order to prevent contamination of the resulting magnesium.

No claim is made herein to the apparatus disclosed, this being the subject matter of a divisional application copending herewith.

I claim:-

1. The process for producing substantially pure magnesium which comprises heating material containing metallic magnesium, to liberate magnesium vapor therefrom, removing the resulting vapor by a non-oxidizing gas from the heated zone, separating out dust from said vapor, and 'thereafter passing it into a condensation zone, and cooling it to condensation point.

2. The process for producing substantially pure magnesium which comprises passing material containing metallic magnesium continuously through a heated zone under reduced pressure, to liberate magnesium vapor therefrom, removing the resulting vapor by a non-oxidizing gas from the heated zone, separating out dust from said vapor, and thereafter passing it into a condensation zone, and cooling it to condensation point.

3. The process for producing substantialiy pure magnesium which comprises heating material containing metallic magnesium under reduced pressure to liberate magnesium vapor therefrom, removing the resulting vaporby a. non-oxidizing gas from the heated zone, separating out dust from said vapor, and thereafter conveying it to a condensation zone, and cooling it to condensation point, premature condensation being preveted by keeping the vapor on its way between the distillation and condensation zone at a temperature above the solidication temperature of metallic magnesium.

4. The process for producing substantially pure magnesium which comprises heating material containing metallic magnesium under reduced pressure to liberate magnesium vapor therefrom,

removing the resulting vapor by a non-oxidizing y gas from the heated zone, separating out dust from said vapor, and thereafter passing it into a condensation zone, and causing it to condense with intermediate liquefaction.

5. The process for producing substantially pure magnesium `which comprises passing material containing metallic magnesium continuously through a heated zone under reduced pressure to drive off magnesium vapor therefrom while leaving behind less volatile concomitant substances, carrying away the resulting magnesium vapor by a non-oxidizing gas from the heating zone, separating out dustA from the flowing vapor, and thereafter conveying it to a condensation zone, and suddenly cooling it to condensation point.

6. The process for producing substantially pure magnesium which comprises heating material containing metallic magnesium, `by continuously passing the material through a heating zone under reduced pressure, nearly to the boiling point of metallic magnesium, to vaporize magnesium while leaving behind impurities not volatile at this temperature, carrying away the resulting magnesium vapor by a non-oxidizing gas from the heating zone, separating out dust. from the flowing vapor, and thereafter conveying it to a condensation zone, and suddenly cooling it to condensation point, premature condensation of the magnesium vapor being prevented by keeping the mixture of non-oxidizing carrier gas and magnesium vapor on its wayfrom the heating zone to the condensation zone, at a temperature above the solidiiication temperature of metallic magnesium.

7. A process for separating magnesiumfrom non-volatile concomitant substances which comprises passing material containing metallic magnesium continuously through a heated zone under reduced pressure to liberate magnesium vapor therefrom, carrying away the disengaged vapor by a non-oxidizing gas from the heated zone, I

flowing vapor, and thereafter passing the vapor into a condensation zone, and suddenly cooling it to condensation point, premature condensation of the magesium being prevented by keeping the vapor on its way between the distillation zone and the cooling zone at a temperature above the solidication temperature of metallic magnesium.

' 9. The process for producing substantially pure magnesium which comprises heating material containing metallic magnesium under reduced pressure to liberate magnesium vapor therefrom, removing the resulting vapor from the heated zone by a non-oxidizing gas, separating dust from said vapor and thereafter passing the vapor into a condensation zone, and cooling the vapor to the condensation point.

10. The process for producing substantially pure magnesium which comprises passing material containing metallic magnesium continuously in a closed system through a heated zone to liberate magnesium vapor therefrom, removing the resulting vapor by a non-oxidizing gas from the heated zone, separating dust from said vapor, thereafter passing the vapor into a condensation zone and cooling it to condensation'point, and maintaining the system under reduced pressure.

l1. The process for producing substantially pure magnesium which comprises heating material containing metallic magnesium under reduced pressure to liberate magnesium vapor therefrom, removing the resulting vapor from the heated zone by a non-oxidizing gas, and while maintaining the system under reduced pressure separating dust from said vapor, conveying the vapor to a condensation zone maintained under reduced pressure and cooling it to condensation point, premature condensation being prevented by keeping the vapor on its way between thekdistillation and condensation zone at a temperature above the solidiiication temperature of metallic magnesium.

12. The process lfor producing substantially pure magnesium which comprises heating material containing metallic magnesium under reduced pressure to liberate magnesium vapor therefrom, removing the resulting vapor from the heated zone by a non-oxidizing gas, and while maintaining the system under reduced pressure separating dust from said vapor, and thereafter while leaving behind impurities not volatile at this temperature, carrying away the Vresulting magnesium vapor from the heating zone by a nonoxidizing gas, separating dust from the owing 5 vapor in the system, and thereafter conveying the vapor to a condensation zone in the system and suddenly cooling it to condensation point, premature condensation of the magnesium vapor being prevented by keeping the mixture of non-oxidizing carrier gas and magnesium vapor on its Way from the heating zone to the condensation zone at a temperature' above the solidification temperature of metallic magnesium, and maintaining the system under reduced pressure.

FRITZ HANSGIRG. 

